A group of independent FDA advisers voted in favor of OK'ing Pfizer ($PFE) and Celltrion's take on the blockbuster inflammation treatment Remicade for all of the reference drug's approved indications, unswayed by protests from Johnson & Johnson ($JNJ).

The agency's arthritis panel voted 21-3 in support of approval for Inflectra, a biosimilar developed by South Korea's Celltrion and co-marketed with Pfizer. In clinical development, the treatment proved itself similar to J&J's Remicade in rheumatoid arthritis and ankylosing spondylitis, and the panel signed off on approving it for psoriatic arthritis, Crohn's disease, ulcerative colitis and psoriasis, as well.

J&J strongly protested approving the biosimilar in Crohn's and ulcerative colitis, which are forms of inflammatory bowel disease (IBD), sending Chief Biotechnology Officer Jay Siegel to testify about differences between Remicade and Inflectra. In prepared remarks, Siegel said Pfizer and Celltrion's clinical data "do not adequately address residual uncertainty regarding use in IBD," as the biosimilar was never compared directly with Remicade in either disease.

But the majority of panelists agreed that there was enough data on how Pfizer and Celltrion's candidate works to extrapolate from the results in arthritis and ankylosing spondylitis, arguing that requiring biosimilar developers to conduct randomized clinical trials in every potential indication would run counter to the spirit of FDA policy.

The FDA is not required to follow the votes of its advisers, though it commonly does. The positive panel outcome puts Pfizer and Celltrion in line for approval by April 6, which would mark the second biosimilar to pass FDA muster after Novartis' ($NVS) take on Amgen's ($AMGN) Neupogen.

J&J CEO Alex Gorsky

For J&J, the potential launch of Inflectra endangers a product that brings in nearly $4.5 billion a year in the U.S. But the company isn't expecting a patent cliff-like effect on sales. Last month, J&J CEO Alex Gorsky told analysts that the drugmaker is confident doctors will be reluctant to switch patients from Remicade to a new, unproven product, adding that the company has seen that play out in markets where the treatment already faces biosimilar competition.

Pfizer inherited the marketing rights to Inflectra in its $17 billion acquisition of Hospira, closed last year. The pharma giant is in the process of selling off its in-house Remicade biosimilar to appease antitrust regulators, betting on Celltrion's version instead.

- read the statement

Editor's note: An earlier version of this story misstated the proposed U.S. name for Pfizer and Celltrion's biosimilar, which is Inflectra. The product is sold as Remsima overseas.